This cross national research concerns ethnic and class stratification and rates of first psychiatric hospitalization. Both Israel and Quebec are excellent examples of multicultural societies where ethnic stratification can be well-studied. Several Jewish ethnic groups in Israel are present in sizable populations in Quebec. This research situation allows exploration of several issues: (1) the effect of ethnic disadvantage on rate of schizophrenia, holding social class constant; (2) the relationship of immigration to rate of schizophrenia; (3) the suggested differences in rates of affective psychosis between Ashkenazic and Sephardic Jews. As well, results reported frequently in the United States will be replicated in these two foreign settings, and other issues will be explored. Data on first psychiatric hospitalization in the Montreal area in 1976 will be collected by examining the records of all hospitals admitting psychiatric patients. Similar data have already been collected for Israel for 1972. The data are classified in identical fashion and virtually 100% complete in Israel and Quebec. The census of Canada and Israel will be used for denominators.